LABORATORY REPORT
Subject of the exercise:
Time domain analysis (Exercise 5.)
Date:
<year>. <month>. <day>
Location:
BME, Q.BP107
Students name:
<name 1>
<name 2>
Group, desk No.
Group <No.>, desk <No.>
Supervisor:
<name>
Measurement instruments
Power supply
Agilent E3630A
Function generator
Agilent 33220A
Oscilloscope
Agilent 54622A
Test board
VIK-05-01
<Serial No.
or label>
< S. No >
Laboratory exercises0.
1. Measurement of time domain parameters of signals
Investigate the step response of the first order low- and high pass filter (VIK-05-01
test board) by different filter parameters (different switch settings)!
<your observations>
This exercise should be accomplished either on passive low- or high pass filter,
depending on the instruction of your tutor. Measure the step response of your
first order filter, with given parameters received from your tutor. The parameters
of the filter can be changed by the switch.
kind of the filter selected by your tutor (lowpass/highpass):
setting of codeswitch selected by your tutor:
1.1.1. Apply a square wave to the input of the filter, and investigate the wave
shapes on the oscilloscope. In order to omit reflections the output
impedance of the generator is 50 , thus, it cannot be considered as
ideal voltage driven generator. Investigate therefore also the input signal
of the filter, and check how close it is to an ideal square wave.
<your observations>
1.1.2. Give a rough estimate for the time constant of the filter based on the
tangent at the zero point.
<your observations>
1.1.3. Estimate the time constant of the filter based on the time the step
response reaches the 50% of the final value! Calculate the error of the
estimate!
1
<your observations>
1.1.4. If you have a low pass filter: estimate the time constant of the filter based
on the time at which the distance between the signal actual value and
the final value decreases by a factor e relative to the final value.
Calculate the error of the estimate!
If you have a high pass filter: estimate the time constant of the filter
based on the time at which the signal actual value decreases be a
factor e relative to the zero value (value at time 0). Calculate the error of
the estimate!
<your observations>
1.1.5. Compare the results of the time constant estimates based on different
methods.
<your observations>
Measure the step response of the active second order low pass filter (same test
board as in the previous exercise) with filter parameters given by your tutor.
Filter parameters can be set by two switches. Do not forget to provide
symmetric power supply to the active circuit, and pay attention on the right
polarity!:
setting of codeswithes selected by your tutor:
R31-40: ................
C1-C11:...............
1.1.6. Apply a square wave to the input of the filter, and investigate the wave
shapes on oscilloscope!
<your observations>
1.1.7. Define and determine the following parameters: rise time, 5% settling
time, under/overshoot!
<your observations>
Measure the phase delay of the passive first order low pass filter at different
frequencies and with different measurement methods. (The filter parameters
should be identical to that of 1.2 exercise.) Accomplish the measurements
based on the following methods: (a) measurement of time delay and period
time with oscilloscope. (b) phase measurement with the built in possibility of the
oscilloscope, (c) phase measurement with oscilloscope based on Lissajous
curve!
1.1.8. Measure the phase delay around the cutoff frequency with the previous 3
methods. Compare the measurement based on different methods.
<your observations>
1.1.9. Calculate the errors of different measurement! ( arcsin x 
1
1  x2
)
<your observations>
1.1.10. Measure the phase delay at 10 different frequencies, distributed evenly
from DC up to 3x the cutoff frequency. (The method of phase
measurement is given by your tutor.) Collect the results in a table. Both
the measured and the calculated values should be documented.
2
<your observations>
1.1.11. Draw the phase diagram!
<your observations>
frequency in kHz
1.2
1
0.8
0.6
0.4
0.2
0
0
0.2
0.4
0.6
0.8
1
1.2
phase in degrees
2. Investigation of reflection on a coaxial cable
Investigate the reflection of signals on a coaxial cable. Apply a square wave to the
cable.
2.1.1. Investigate the reflection by different loads (short circuit, open circuit,
matched, unmatched, capacitive load)! Document the wave shapes!
<your observations>
2.1.2. Calculate the propagation speed from the reflection time and the known
length of the cable! Calculate the relative dielectric constant of the cable.
(The propagation speed of the light in vacuum is c  3  108 m .)
s
<your observations>
2.1.3. Investigate the reflection if the impedances on both sides of the cable are
unmatched. Document the wave shape!
<your observations>
2.1.4. Determine the location and kind of fault of a cable receive from your
tutor. Calculate the error of the measurement!
<your observations>
Additional Laboratory Exercises
3. Averaging as noise suppression
Get acquainted with the averaging function of the oscilloscope. Generate noisy
periodic signal! The signal to noise ratio can be worsen the most easily by
reducing the amplitude of the signal generator (setting a very low signal
amplitude, at which the signal level is comparable to the level of the ambient
noise). Set the function generator to produce a periodic triangular waveform
with 1 kHz frequency and 100% symmetry, and reduce the amplitude to the
least possible value (20 mVpp peak-to-peak)! Trigger the oscilloscope to the
rising edge of the waveform!
3
3.1.1. Investigate the waveform without and with averaging! Use the function
generators SYNC output as trigger source! Measure the peak value of
the signal in both cases!
<your observations>
3.1.2. Accomplish the averaging first by using the noisy waveform as trigger
source, then by using a noise free source (SYNC output of the signal
generator)! What is your observation?
<your observations>
3.1.3. Repeat the previous measurement with square wave signal! What is your
observation?
<your observations>
4